Heat interchanger



June 1967 A. E. KOVALIK ETAL 3,327,777

HEAT INTERGHANGER Filed Nov. 9, 1964 2 Sheets-Sheet 1 INVENTORS ALBERTE. KOVALIK SAMUEL H.S. RAUB June 1967 A. E. KOVALIK ETAL 3,

HEAT INTERCHANGER 2 Sheets-Sheet 2 Filed Nov. 9, 1964 INVENTORS ALBERTE. KOVALIK SAMUEL H.S.RAUB

United States Patent O 3,327,777 HEAT INTERCHANGER Albert E. Kovalik,Cleveland, and Samuel H. S. Raub,

Bay Village, Ohio, assignors to Union Carbide Corporation, a corporationof New York Filed Nov. 9, 1964, Ser. No. 409,861 Claims. (Cl. 165-81)The present invention relates, in general to improvements in heatexchangers, and in particularly, to heat exchangers of the shell andtube type, and more particularly to totally enclosed tube bundle heatexchangers of the character containing non-metallic tubes of carbon orgraphite construction for conducting corrosive fluid media.

The particular improvement advanced by this invention is directed tonovel and improved floating head arrangements.

An excellent heat interchanger of the totally enclosed type whereincertain gaskets are sealed by spring pressure means internally mountedis disclosed in copending United States application Ser. No. 409,860,filed Nov. 9, 1964, the assignee of the subject invention being'also theassignee of the above-referred to application. The heat exchangerdisclosed in the copending application comprises a totally enclosed orarmored tube type exchanger wherein a carbonaceous tube bundle isfixedly held at one end of the shell and floating supported at the otherend thereof. Resilient loading means such as compression springs arepositioned within the shell such that the springs and hydraulic pressureimpressed by the shell side fluid act in the same direction against thefloating end of the tube bundle to compressively load the carbonaceoustubes and to increase the effectiveness of gasket sealing.

This type of heat exchanger like all exchangers, may, by reason ofimproper use require some maintenance or repair, particularly of themetallic elements or the internally mounted resilient means since theshell side fluid which flows in and around the springs may be corrosivesaline water in contrast to fresh water, thus these elements could besubject to corrosion. In addition, when replacing a defective spring onemust dismantle most of the floating end of the heat exchanger.

It is, therefore, the principal object of the invention to overcome thedisadvantages of the prior art heat exchangers and to provide a floatinghead arrangement including a tube sheet and closure therefor, whereinthe gaskets between the end domes or covers and the tube sheets on bothends of the enclosed tube bundle, and the gaskets between the fixed endplate and the fixed cover are exclusively sealed by spring pressure onthe floating end. The use of externally mounted springs in thisapplication is unique in that they maintain the abovenoted gaskets leaktight under all operating conditions of temperature and pressure andthey they are readily accessible for ordinary servicing and are not incontact with any fluid media. The tube bundle comprising a plurality oftubes is conventionally stayed by 'bafiles spaced on normal centersalong the tube length.

Since the invention is primarily concerned with a floating heatstructure arrangement to be used with the more or less conventional'forms of totally enclosed tube bundle heat exchangers, the otherportions of such exchanger including the shell and the fixed end of thetube bundle although shown in the accompanying drawings will not bedescribed in great detail since such heat exchangers are well known andunderstood by those skilled in the art.

The primary object and other objects and advantages of the inventionwill be readily understood from the following detailed description whenread in conjunction with the accompanying drawing, which illustrates thepreferred forms of the heat interchanger, and in which like charac-3,327,777 Patented June 27, 1967 ters of reference designates like partsthroughout the several views, and in which:

FIG. 1 is a side elevation view, partly in section, show ing thepreferred form of the invention;

FIG. 2 is another side elevational view, partly in sec- 7 ti-on showinganother form of the invention; and

FIG. 3 is a greatly enlarged fragmentary view, largely in sectionshowing the floating end of yet another modified exchanger similar tothe exchanger of FIG. 2.

Referring now to the drawings, and particularly to FIG. 1, there isshown a two pass heat exchanger of the shell and tube type generallyindicated by the numeral 10. A combined fixed inlet and outlet end domeor cover 12 and a fixed tube sheet 14, both of impervious carbon orgraphite, are rigidly aflixed to the longitudinal metallic shell 16 ofthe heat exchanger 10 'by means of flange 18, end plate 20 and suitabletie-rods and bolts, 22 and 24 respectively. Within the shell 16 ismounted a bundle of uniformly disposed impervious carbon or graphitetubes 26, which pass through correspondingly spaced holes in bafiles(not shown). The fixed tube sheet 14 supports one end of the tubes 26.

Floating tube sheet 30 is in juxtaposition with a closed two passfloating dome or cover 32 also of carbon or graphite. The tubes 26 as isdone in the art are conventionally cemented into open-ended sockets inthe tube sheets 14 and 30.

A flange 34 is conventionally secured to the shell 16, such as bywelding, and a seal ring 36 which maintains the packing or gasket 38 inplace is suitably fastened tightly to flange 34 with the usualconnecting rods and bolts 40 and 42.

The improved feature of the heat exchanger 10 of the invention centersaround the floating head arrangement or floating end members whichpermit the tube bundle (tube sheets, tube 'bafiles, etc.) to be undercontinuous compressive loading and seal-s the gaskets 44 and 46 betweenthe covers 12 and 32 and tube sheets 14 and 30, and the gasket 48between the fixed cover 12 and fixed end plate 20. Gasket 50' alsoprovides a seal between flange 18 and fixed tube sheet 14.

A plurality of externally mounted compression springs 52 are positionedabout the periphery of end plate 54. Guide and support studs 56 whichbear against and maintain the springs 52 in place against the end plate54 are locked by means of nuts 57 to flange 34. The springs 52 bearagainst the end plate 54, a gasket-like bearing disk 58 disposed betweenthe end 60 of the floating cover 32 which is seated against the floatingtube sheet 30. The floating tube sheet 30 in turn bears toward the fixedtube sheet 14, thus loading the tubes 26 in compression.

It is important to note that the end plate 54 is provided with aprojecting tube like element 62 which is adapted to closely fit aboutthe end 60 of the floating cover 32. This element 62 not only rendersthe floating head arrangement totally enclosed, but it acts inconjunction with the packing 38 located between the seal ring 36 andflange 34 to preclude the shell side fluid from leaking out between theseal ring 36 and the tube-like element 62 and from gaining access to thefar end 60 of the floating cover 32. Thus, no hydraulic pressure can beimpressed against the cover 32 in the direction of the spring loading.

Since carbon and graphite is much stronger in compression than intension, it is highly advantageous to utilize the invention for suchshell and tube type heat exchangers employing a tube bundle assembly.Moreover, continuous spring loading follows the gasket material underall conditions of cold flow, maintains pres-sure over full range ofdifferential thermal expansion, and eliminates complete relaxation ofbolt loading which occurs when the bolt heads rust against their bearingsurfaces or when the nuts vibrate loose. Further, the spring loadingunder these conditions control the gasket loading as opposed to theexcessive and variable bolt loading necessary when standard bolts areused to seal the gaskets. Since all of the carbonaceous members aretotally enclosed within the shell structure the heat exchanger of theinvention can be considered of armored construction.

In FIGURE 2, there is shown a modified form of the heat exchanger of theinvention. In this view, the objects of the invention are illustrated asapplied to a single pass shell and tube type heat exchanger 66. Thisembodiment is very similar to the exchanger of FIG. 1 except for thecovers and in the arrangement of the floating head. At the fixed end 68of the heat exchanger 66 the fixed carbon or graphite tube sheet 70 andthe fixed dome or cover 72 is fixedly secured to the shell 74 and fixedend plate 78 by conventional securing means, such as nuts and bolts 80and 82, respectively. The carbon or graphite tubes 84 joining the fixedtube sheet 70 and the floating tube sheet 86 are, of course, as isconventionally done in the art, stayed and braced by suitable baflies(not shown).

Gaskets 88 and 90 are respectively located between floating cover 92 andfloating tube sheet 86 and the fixed end tube sheet 70 and cover 72.These gaskets as well as gasket 94 disposed between the fixed cover 72and fixed end plate 78 are similarly held under compressive loading by aplurality of springs 96 which bear against the floating end plate 98,and a gasket-like bearing disk which in turn bears against the floatingcover 92.

In this modification, flange 102 which is suitably welded to the shell74, is used as the anchoring means for the seal ring 106 and thefloating end plate and projecting tube-like element 98 and 108respectively. Seal ring 106 maintains packing or gasket 112 in place,which gasket precludes shell side fluid leakage from between the sealring 106 and tube-like element 108. The seal ring 106 also contributesin totally enclosing the heat exchanger, if desired, seal ring 106 canbe eliminated if gasket 112 is placed in a suitable groove or channel.Of course, the tube sheet and cover must still be enclosed by othermeans such as a sleeve like exterior of the flange which would telescopeinside the tube-like element 108. As mentioned in connection with FIG.1, there also is no hydraulic pressure impressed against the cover 92 inthis modification.

If desired because of space requirements or other reasons, the springs96 may be located on the opposite side 110 of the flange 102 as shown bythe phantom (dotted) lines. This of course, would facilitate access tothe end plate 98 more readily, particularly when assembling a conduit tothe floating end plate studs 114. Regardless of where the springs aremounted, they must still be unloaded when removing either the fixed orfloating cover.

FIGURE 3 shows the construction of another modified floating headarrangement of a totally enclosed tube bundle heat exchanger. Thestructure of this partially shown heat exchanger is similar to thatdescribed in connection with FIG. 2, but differs in that the end plate118 is limited in diameter to about the size of the shell 120 and aperipheral flange 122 is provided about the end 124 of the tube-likeelement 126. These parts are conventionally secured together, such as bywelding and the peripheral flange 122 is employed as a bearing surfacefor springs 128 which are guided and supported by studs 130 locked bymeans of nuts 132 to flange 134.

The advantages of the invention may be summarized as follows: theimproved heat exchanger provides compressive spring loading as opposedto the excessive and variable bolt loading necessary when standard boltsare used to seal the gaskets in heretofore totally enclosed tube bundleheat exchangers, spring loading of the gaskets is provided for under allconditions of cold flow, uniform pressure is maintained over full rangeof differential thermal expansion and relaxation of bolt loading which 4occurs when the bolt heads rust against their hearing surfaces or whenthe nuts vibrate loose is eliminated.

What is claimed is:

1. A heat exchanger, comprising a shell, a tube bundle therein, afloating tube sheet for slidably supporting one end of said tube bundlewithin said shell, a flange on said shell at the floating tube sheet endthereof, a floating cover abutting said floating tube sheet, an endplate for the floating end of said heat exchanger, a tube elementsecured to said end plate, said tube element being adapted V to closelyfit about the endof said floating cover whereby shell side fluid isprevented from leaking out of said exchanger and whereby hydraulicpressure is prevented from being impressed against saidcover, andresilient loading means disposed about means for securing said end plateto said flange for loading the tubes of said tube bundle compressively.

2. The heat exchanger of claim 1 wherein said resilient means comprise aplurality of compression springs positioned about a plurality of studswhich maintain said compression springs in place against said end plate.

3. A heat exchanger, comprising a shell, a tube bundle therein, a fixedtube sheet for supporting one end of said tube bundle Within said shell,a fixed cover and a gasket between said fixed tube sheet and said fixedcover, a floating tube sheet for slidably supporting the opposite end ofsaid tube bundle within said shell, 21 flange on said shell at thefloating tube sheet end thereof, a floating cover and a second gasketbetween said floating tube sheet and said floating cover, an end platefor the floating end of said heat exchanger, a tube element secured tosaid end plate, said tube element being adapted to closely fit about theend of said floating cover whereby shell side fluid is prevented fromleaking out of said exchanger and whereby hydraulic pressure isprevented from being impressed against said cover, and resilient loadingmeans disposed about means for securing said end plate to said flangefor loading said gaskets compressively.

4. A heat exchanger, comprising -a shell, a tube bundle therein, a fixedtube sheet for supporting one end of said tube bundle within said shell,a fixed cover and a gasket between said fixed tube sheet and said fixedcover, an end plate for the fixed end of said heat exchanger and asecond gasket between said fixed cover and said end plate, a floatingtube sheet for slidably supporting the opposite end of said tube bundlewithin said shell, a flange on said shell at the floating tube sheet endthereof, a floating cover and a third gasket between said floating tubesheet and said floating cover, a second end plate for the floating endof said heat exchanger, a tube element secured to said end plate, saidtube element being adapted to closely fit about the end of said floatingcover whereby shell side fluid is prevented from leaking out of saidexchanger and whereby hydraulic pressure is prevented from beingimpressed against said cover, and resilient loading means disposed aboutmeans for securing said end plate to said flange for loading saidgaskets compressively.

5. A heat exchanger, comprising a shell, a tube bundle therein, animpervious carbonaceous tube sheet fixed to one end of said shell forsupporting one end of said tube bundle Within said shell, an impreviouscarbonaceous fixed cover and a gasket between said fixed tube sheet andsaid fixed cover, an impervious carbonaceous floating tube sheet forslidably supporting the opposite end of said tube bundle within saidshell, a flange on said shell at the floating tube sheet end thereof, animpervious carbonaceous floating cover and a second gasket between saidfloating tube sheet and said floating cover, an end plate for thefloating end of said heat exchanger, a tube element secured to said endplate, said tube element being adapted to closely fit about the end ofsaid floating cover whereby shell side fluid is prevented from leakingout of said exchanger and whereby hydraulic pressure is prevented frombeing impressed against said cover and resilient loading means disposedabout means for securing said end plate to said flange for loading saidgaskets and the tubes of said tube bundle compressively.

6. A heat exchanger comprising a shell, an impervious carbonaceous tubesheet fixed to one end of said shell, an impervious carbonaceousfloating tube sheet at the opposite end of said shell, a bundle ofsubstantially parallel impervious carbonaceous tubes extending betweensaid tube sheets and communicating with corresponding openended socketsin said tube sheets, a flange on said shell at the floating tube sheetend thereof, an impervious carbonaceous floating cover abutting saidfloating tube sheet, an end plate for the floating end of said heatexchanger, a tube element secured to said end plate, said tube elementbeing adapted to closely fit about the end of said floating coverwhereby shell side fluid is prevented from leaking out of said exchangerand whereby hydraulic pressure is prevented from being impressed againstsaid cover, and externally mounted resilient loading means disposedabout means for securing said end plate to said flange for loading saidtubes compressively between said tube sheets.

7. The heat exchanger of claim 6 wherein said resilient means comprise aplurality of compression springs positioned about a plurality of studswhich maintain said compression springs in place against said end plate.

8. A heat exchanger comprising a shell, a tube bundle therein, afloating tube sheet for slidably supporting one end of said tube bundlewithin said shell, a flange on said shell at the floating tube sheet endthereof, a floating cover abutting said floating tube sheet, an end.plate and housing for substantially covering said floating cover, atube element secured to said end plate, said tube element being adaptedto closely fit about the end of said floating cover whereby shell sidefluid is prevented from leaking out of said exchanger and wherebyhydraulic pressure is prevented from being impressed against said cover,a gasket disposed between said floating tube sheet and said flange, aring for maintaining said gasket in place secured to said flange, andresilient lOading means disposed about means for securing said end plateto said flange for compressively loading the tubes of said tube bundle.

9. A heat exchanger comprising a shell, a tube bundle therein, afloating tube sheet for slidably supporting one end of said tube bundlewithin said shell, a flange on said shell at the floating tube sheet endthereof, a floating cover abutting said floating tube sheet, an endplate and tubular shaped sleeve for substantially covering said floatingcover, a tube element secured to said end plate, said tube element beingadapted to closely fit about the end of said floating cover wherebyshell side fluid is prevented from leaking out of said exchanger andwhereby hydraulic pressure is prevented from being impressed againstsaid cover, a gasket disposed between said floating tube sheet and saidflange, a ring secured to said flange disposed between said tubularshaped sleeve and said floating tube sheet and said cover formaintaining said gasket in place and resilient loading means disposedabout means for securing said end plate to said flange for compressivelyloading the tubes of said tube bundle.

10. A totally enclosed heat exchanger comprising a shell, a tube bundletherein, a floating tube sheet for slidably supporting one end of saidtube bundle Within said shell, a flange on said shell at the floatingtube sheet end thereof, a floating cover abutting said floating tubesheet, an end plate and housing for substantially covering said floatingcover, a tube element secured to said end plate, said tube element beingadapted to closely fit about the end of said floating cover wherebyshell side fluid is prevented from leaking out of said exchanger andwhereby hydraulic pressure is prevented from being impressed againstsaid cover, a gasket disposed between said floating members and saidflange, and resilient loading means disposed about means for securingsaid end plate to said flange for compressively loading the tubes ofsaid tube bundle.

References Cited UNITED STATES PATENTS 464,159 12/1891 Link -82 826,9667/1906 Schneible 16582 1,591,174 7/1926 Mailey 165-81 X 2,887,303 5/1959Reys 16582 2,956,787 10/ 1960 Raub 165-82 3,221,808 12/1965 Pyle 165158FOREIGN PATENTS 1,211,918 10/ 1959 France.

908,028 4/ 1954 Germany.

929,701 6/ 1963 Great Britain.

ROBERT A. OLEARY, Primary Examiner. A. W. DAVIS, Assistant Examiner.

1. A HEAT EXCHANGER, COMPRISING A SHELL, A TUBE BUNDLE THEREIN, AFLOATING TUBE SHEET FOR SLIDABLY SUPPORTING ONE END OF SAID TUBE BUNDLEWITHIN SAID SHELL, A FLANGE ON SAID SHELL AT THE FLOATING TUBE SHEET ENDTHEREOF, A FLOATING COVER ABUTTING SAID FLOATING TUBE SHEET, AN ENDPLATE FOR THE FLOATING END OF SAID HEAT EXCHANGER, A TUBE ELEMENTSECURED TO SAID END PLATE, SAID TUBE ELEMENT BEING ADAPTED TO CLOSELYFIT ABOUT THE END OF SAID FLOATING COVER WHEREBY SHELL SIDE FLUID ISPREVENTED FROM LEAKING OUT OF SAID EXCHANGER AND WHEREBY HYDRAULICPRESSURE IS PREVENTED FROM BEING IMPRESSED AGAINST SAID COVER, ANDRESILIENT LOADING MEANS DISPOSED ABOUT MEANS FOR SECURING SAID END PLATESO SAID FLANGE FOR LOADING THE TUBES OF SAID TUBE BUNDLE COMPRESSIVELY.